In internal combustion engines, the engine crankshaft translates power generated in the combustion and expansion strokes of the engine cylinders and converts the power to torque. The torque output from the engine is delivered from the crankshaft through a torque transmission device to provide motive force. For example, in a motor vehicle, the crankshaft provides torque to the drivetrain of the vehicle; in a marine vehicle, the crankshaft provides torque to a propulsion system; in a power generation device, the crankshaft provides torque to a rotor that rotates within a stator.
Throughout operation of the engine, the torque applied to the crankshaft varies due to, for example, periodic firing of the engine's cylinders, variation in the crankshaft rotational speed, and engagement and disengagement of transmission elements. These torque variations may create torsional vibrations in the crankshaft that may tend to periodically twist the crankshaft. Twisting of the crankshaft by the torque variations may increase vibrations that are imparted to the transmission elements, which may increase bearing wear, as well as adversely affect engine timing caused by variations in the piston position relative to the end of the crankshaft. Further, twisting of the crankshaft may increase mechanical stress in the crankshaft itself, which may lead to failure of the crankshaft.
Accordingly, dampers for crankshafts of reciprocating engines may be desired to mitigate torsional vibrations in the crankshafts.